Coordinator of Laboratory Programs
Department of Biology
The University of Mississippi
Office: 422 Shoemaker Hall
Telephone: (662) 915-5786
Spiders have long been my main research focus as they are an amazingly diverse group of organisms. Spiders have clear and unambiguous synapomorphies (the evolution of the spigots and spinnerets and their use of silk) yet, at the level of families, relationships are still not clear. Spiders represent a "megadiverse" group rivaling some of the large insect orders with credible estimates of over 100,000 species, but unlike the other large orders of arthropods, they are the only such group to be entirely predatory. Their predatory nature makes them particularly interesting for studies focusing on courtship and sexual selection: selection pressure in the form of cannibalism can be swift.
My research spans four areas:
1) the nature of a species, species concepts and speciation,
2) evolution of behavior and the importance of behavior in evolution,
3) Systematics of wolf spiders including species descriptions and phylogenetic studies and
4) the effects of fragmentation of habitat and small population size on fitness parameters.
Recent projects include:
1. Evolution of rowing behavior in spiders:
The Pisauridae or fishing spiders have a remarkable ability to row on the surface of water. How they are able to do this has been explored by Dr. Robert Suter of Vassar College .
With Bob Suter and Pat Miller, we have been exploring what other spiders can move on water by rowing. We have tested hundreds of spiders in 40 families for their ability to row and have now mapped the ability onto cladograms of spiders. The ability to row has apparently evolved independently at least 6 times and has been lost numerous times in the wolf spiders. Full text. In addition, several groups of spiders have distinct gaits (other than rowing) on the water surface Full text.
Compare the movement of a Dolomedes triton, with Geolycosa rogersi, a salticid and a tetragnathid.
In order for spiders to be capable of staying on the surface of water, their cuticle must be hydrophobic. Compare the images of various arthropods showing different amounts of hydrophobicity.
2. Phylogeny of Geolycosa
The Geolycosa are obligate burrowing wolf spiders that are most diverse in the southeast, particularly Florida. With Sam Marshall, Randy Hoeh and Pat Miller, I am working on understanding their phylogeny. As part of this effort, we are building a library of images for each species in this group.
3. Effects of population size and habitat fragmentation of Rabidosa wolf spiders
Rabidosa spp. are large wolf spiders found throughout the eastern United States. With David Reed and Rich Buchholz we are looking at many aspects of Rabidosa biology.
4. Phylogeny of Schizocosa
Schizocosa are a fascinating genus of wolf spiders. Several species have conspicuous secondary sexual characteristics that take the form of pigment and or bristles on the tibia of mature males. The secondary sexual characteristics have proved to be useful in recognizing new species and there is a strong correlation between the form of the bristles and reproductive isolation between groups and studies of these have led to the description of several new species (studies by Stratton as well as Uetz and Dondale). Two of the brush-legged species show geographic variation in behavior with some reduction in interbreeding between geographically separated populations (studies by Miller, Stratton, Miller and Hebets). There may be asymmetry in reproductive isolation (unpublished data for S. crassipes studies by Germano, Stratton, Miller and Miller) suggesting that these species are diversifying.
5. Functional morphology
Among the most remarkable spiders are the eponymous spitting spiders (family Scytodidae) who subdue their prey with material ejected from their chelicerae. Bob Suter and I have compared the morphology of spitting spiders with that of wolf spiders to see what tradeoffs have been made by each of the divergent groups of spiders.